多巴胺受体在腹外侧眶皮层诱发抗伤害感受性效应中的作用

Effect of dopamine receptors on the ventrolateral orbital cortex induced antinociception

目的研究多巴胺D1和D2样受体是否参与腹外侧眶皮层(VLO)诱发的抗伤害感受性效应。方法将一伤害性热刺激施加于浅麻醉大鼠尾部诱发甩尾(TF)反射,以TF反射潜伏期(TFL)为指标观察VLO内微量注射不同药物对这一指标的影响。结果 VLO内微量注射多巴胺D1样受体激动剂SKF-38393(1.0、5.0μg)对TF反射没有影响,TFL维持在基线水平;而给予多巴胺D2样受体激动剂喹吡罗(0.1～2.0μg)可以产生剂量依赖性抗伤害感受性效应,不同处理组TFL相继增加的顺序为0.1μg组=0.5μg组<1.0μg组<1.5μg组<2.0μg组,该抑制效应能被VLO内相同注射位点预先注射多巴胺D2样受体拮抗剂雷氯必利(1.5μg)所阻断;VLO内单独注射雷氯必利(1.5μg)不改变TFL的基础值。结论多巴胺D2样受体可能参与激活VLO诱发的抗伤害感受性效应。

Objective To examine whether activation of Dl -like and D2-1ike dopamine receptors are involved in the ventrolateral orbital cortex （VLO） induced antinoeiception. Methods A damaging thermal stimulation was applied on rats tail lightly anesthetized to evoke tail flick（TF） reflex. Using TF latency （TFL） as an index, the effect of microinjection of different drugs were observed in VLO. Results Microinjeetion of the D1 -like dopamine receptors agonist SKF-38393 （ 1.0,5.0 μg） in VLO didn＇t change the baseline of TFL. But microinjection of the D2-1ike dopamine receptor agonist quinpirole（O. 1 -2.0 ~g） into VLO produced dose-dependent antinociception. The order of the TFL increases in different treated groups were O. 1 txg group = 0.5 μg group 〈 1.0 μg group 〈 1.5 μg group 〈 2.0 μg group. This antinoeiception was antagonized by D2-like dopa- mine receptor antagonist raclopride（ 1.5 μg） in VLO at the same site of injection. Raclopride（ 1.5μg） mieroinjected alone into the VLO had no effect on the TF reflex. Conclusion D2-like dopamine receptor activation may be involved in the VLO in- duced antinociception.